The openness calculation is the IBC test determining whether a parking structure qualifies as open: each tier needs openings on at least 40% of its perimeter wall area, distributed on at least 20% of the perimeter (per the code’s uniform-distribution provisions). In a parking facility:
- Open classification eliminates mechanical ventilation and most sprinkler mandates in many jurisdictions, with large capital consequences.
Considerations
- Facade and screening choices can quietly break openness; run the numbers before the architecture settles. Openness is a math problem with a mechanical-system prize.